Cyprinid herpesvirus 3 (CyHV 3) is causing severe economic losses worldwide in common and koi carp industries, and a safe and efficacious attenuated vaccine compatible with mass vaccination is needed. We produced single deleted recombinants using prokaryotic mutagenesis. When producing a recombinant lacking open reading frame 134 (ORF134), we unexpectedly obtained a clone with additional deletion of ORF56 and ORF57. This triple deleted recombinant replicated efficiently in vitro and expressed an in vivo safety/efficacy profile compatible with use as an attenuated vaccine. To determine the role of the double ORF56-57 deletion in the phenotype and to improve further the quality of the vaccine candidate, a series of deleted recombinants was produced and tested in vivo. These experiments led to the selection of a double deleted recombinant lacking ORF56 and ORF57 as a vaccine candidate. The safety and efficacy of this strain were studied using an in vivo bioluminescent imaging system (IVIS), qPCR, and histopathological examination, which demonstrated that it enters fish via skin infection similar to the wild type strain. However, compared to the parental wild type strain, the vaccine candidate replicated at lower levels and spread less efficiently to secondary sites of infection. Transmission experiments allowing water contamination with or without additional physical contact between fish demonstrated that the vaccine candidate has a reduced ability to spread from vaccinated fish to naïve sentinel cohabitants. Finally, IVIS analyses demonstrated that the vaccine candidate induces a protective mucosal immune response at the portal of entry. Thus, the present study is the first to report the rational development of a recombinant attenuated vaccine against CyHV 3 for mass vaccination of carp. We also demonstrated the relevance of the CyHV 3 carp model for studying alloherpesvirus transmission and mucosal immunity in teleost skin. [less ▲]

Endosomes have important roles in intracellular signal transduction as a sorting platform. Signaling cascades from TLR engagement to IRF3-dependent gene transcription rely on endosomes, yet the proteins ... [more ▼]

Endosomes have important roles in intracellular signal transduction as a sorting platform. Signaling cascades from TLR engagement to IRF3-dependent gene transcription rely on endosomes, yet the proteins that specifically recruit IRF3-activating molécules to them are poorly defined. We show that adaptor protein containing a pleckstrin-homology domain, a phosphotyrosine-binding domain, and a leucine zipper motif (APPL)1, an early endosomal protein, is required for both TRIF- and retinoic acid–inducible gene 1–dependent signaling cascades to induce IRF3 activation. APPL1, but not early endosome Ag 1, deficiency impairs IRF3 target gene expression upon engagement of both TLR3 and TLR4 pathways, as well as in H1N1-infected macrophages. The IRF3-phosphorylating kinases TBK1 and IKK« are recruited to APPL1 endosomes in LPS-stimulated macrophages. Interestingly, APPL1 undergoes proteasome-mediated degradation through ERK1/2 to turn off signaling. APPL1 degradation is blocked when signaling through the endosome is inhibited by chloroquine or dynasore. Therefore, APPL1 endosomes are critical for IRF3-dependent gene expression in response to some viral and bacterial infections in macrophages. Those signaling pathways involve the signal-induced degradation of APPL1 to prevent aberrant IRF3-dependent gene expression linked to immune diseases. [less ▲]

Myxoma virus (MYXV) induces a lethal disease called Myxomatosis in European rabbits. MYXV is one of the rare viruses that encodes an alpha2,3-sialyltransferase through its M138L gene. In this study, we ... [more ▼]

Myxoma virus (MYXV) induces a lethal disease called Myxomatosis in European rabbits. MYXV is one of the rare viruses that encodes an alpha2,3-sialyltransferase through its M138L gene. In this study, we showed that although the absence of the enzyme was not associated with any in vitro deficit, the M138L deficient strains are highly attenuated in vivo. Indeed, while all rabbits infected with the parental and the revertant strains died within 9 days post-infection from severe myxomatosis, all but one rabbit inoculated with the M138L deficient strains survived the infection. In primary lesions, this resistance to the infection was associated with an increased ability of innate immune cells, mostly neutrophils, to migrate to the site of virus replication at 4 days post-infection. This was followed by the development of a better specific immune response against MYXV. Indeed, at day 9 post-infection, we observed an important proliferation of lymphocytes and an intense congestion of blood vessels in lymph nodes after M138L knockouts infection. Accordingly, in these rabbits, we observed an intense mononuclear cell infiltration throughout the dermis in primary lesions and higher titers of neutralizing antibodies. Finally, this adaptive immune response provided protection to these surviving rabbits against a challenge with the MYXV WT strain. Altogether, these results show that expression of the M138L gene contributes directly or indirectly to immune evasion by MYXV. In the future, these results could help us to better understand the pathogenesis of myxomatosis but also the importance of glycans in regulation of immune responses. [less ▲]

Cycloviruses, small ssDNA viruses of the Circoviridae family, have been identified in the cerebrospinal fluid from symptomatic human patients. One of these species, cyclovirus-Vietnam (CyCV-VN), was shown ... [more ▼]

Cycloviruses, small ssDNA viruses of the Circoviridae family, have been identified in the cerebrospinal fluid from symptomatic human patients. One of these species, cyclovirus-Vietnam (CyCV-VN), was shown to be restricted to central and southern Vietnam. Here we report the detection of CyCV-VN species in stool samples from pigs and humans from Africa, far beyond their supposed limited geographic distribution. [less ▲]

The “hygiene hypothesis” proposes that the augmentation of allergic diseases in developed countries could be linked to a reduced exposure to infections during childhood. Surprisingly, the potential ... [more ▼]

The “hygiene hypothesis” proposes that the augmentation of allergic diseases in developed countries could be linked to a reduced exposure to infections during childhood. Surprisingly, the potential protective role of herpesvirus infections against allergy development has never been addressed directly. In this study, we used the Murid herpesvirus 4 (MuHV-4) to study the impact of a persistent gammaherpesvirus infection on the development of House Dust Mites (HDM)-induced allergic asthma. Our results revealed that MuHV-4 infection affects both the sensitization and the challenging phases of HDM-induced airway allergy. In particular, we highlighted that MuHV-4 infection strongly impacts the lung innate immune response. Indeed, while the dendritic cells remained competent to uptake antigens and to migrate to the draining lymph nodes, MuHV-4 infection impaired their ability to trigger HDM sensitization. In the future, these results could allow us to develop strategies to prevent the development of TH2-skewed responses against respiratory allergens. [less ▲]

DBA/2J and C57BL/6J represent two opposite ends in terms of sensitivity and resistance to influenza A virus between the Mx-negative mouse lines. Several research teams focused on the factors explaining ... [more ▼]

DBA/2J and C57BL/6J represent two opposite ends in terms of sensitivity and resistance to influenza A virus between the Mx-negative mouse lines. Several research teams focused on the factors explaining this difference, mainly by genetic approaches using Recombinant Inbred Lines between those two strains. Several candidate-genes have been proposed, but it was not possible to determine their importance. To help to define the factors involved in the susceptibility of DBA/2J mice to influenza infection, we adopted a phenotypic approach to identify the critical steps of the infection process accounting for this extreme susceptibility. Overall, the data presented here support the role of a dysfunction of alveolar macrophages, to influenza infection in the higher susceptibility of DBA/2J mice to this virus. [less ▲]

We comprehensively surveyed morphologic alterations in calves naturally infected in utero by Schmallenberg virus (SBV) and born deformed. SBV-specific RNA was distributed unevenly in different tissues ... [more ▼]

We comprehensively surveyed morphologic alterations in calves naturally infected in utero by Schmallenberg virus (SBV) and born deformed. SBV-specific RNA was distributed unevenly in different tissues. Implications for diagnosic procedures are highlighted. [less ▲]

DBA/2J and C57BL/6J represent two opposite ends in terms of sensitivity and resistance to influenza A virus between the Mx-negative mouse lines. Several research teams focused on the factors explaining ... [more ▼]

DBA/2J and C57BL/6J represent two opposite ends in terms of sensitivity and resistance to influenza A virus between the Mx-negative mouse lines. Several research teams focused on the factors explaining this difference, mainly by genetic approaches using Recombinant Inbred Lines between those two strains. Several candidate-genes have been proposed, but it was not possible to determine their importance. To help to define the factors involved in the susceptibility of DBA/2J mice to influenza infection, we adopted a phenotypic approach to identify the critical steps of the infection process accounting for this extreme susceptibility. Overall, the data presented here support the role of a dysfunction of alveolar macrophages, to influenza infection in the higher susceptibility of DBA/2J mice to this virus. [less ▲]

In October 2012, a 3-year-old bullfinch (Pyrrhula pyrrhula) held in captivity for its entire lifespan and a wild adult great spotted woodpecker (Dendrocopos major), both with neurological signs, were ... [more ▼]

In October 2012, a 3-year-old bullfinch (Pyrrhula pyrrhula) held in captivity for its entire lifespan and a wild adult great spotted woodpecker (Dendrocopos major), both with neurological signs, were found 4 km from each other and 5 days apart in the Meuse Valley, Belgium. Non-suppurative encephalitis and mild degeneration and necrosis were identified in the brain and cerebellum, and Usutu virus antigen and RNA were detected by immunohistochemistry and real-time reverse transcriptase PCR, respectively. The two cases reported here represent the most western distribution of clinical disease in birds due to Usutu virus. [less ▲]

During the last decades, metagenomic studies expanded the numbers of newly described, often unclassified, viruses within the Circoviridae family. Using broad-spectrum circo-/cyclovirus PCRs, we ... [more ▼]

During the last decades, metagenomic studies expanded the numbers of newly described, often unclassified, viruses within the Circoviridae family. Using broad-spectrum circo-/cyclovirus PCRs, we characterized a novel circo-like virus in Aedes vexans mosquitoes from Germany whose main putative open reading frames (ORFs) shared very low amino acid identity with those of previously characterized circo-/cycloviruses. Phylogenetic and genetic distance analysis revealed that this new virus species defines, with previously described mosquito- and bat feces-derived circo-like viruses, a different genus, tentatively called "krikovirus", within Circoviridae. We further demonstrated that viruses of the putative krikovirus genus all share a genomic organization which is unique among Circoviridae. Further investigations are needed to determine the host range, tissue tropism and transmission route(s). This report increases the current knowledge of the genetic diversity and evolution of the members of the Circoviridae family. [less ▲]

Schmallenberg virus, a novel orthobunyavirus, is spreading among ruminants, especially sheep and cattle throughout Europe. To determine the risk for domestic dog infection, we conducted a survey among ... [more ▼]

Schmallenberg virus, a novel orthobunyavirus, is spreading among ruminants, especially sheep and cattle throughout Europe. To determine the risk for domestic dog infection, we conducted a survey among cases referred to the university Companion Animal Clinic to assess possible seroconversion. No evidence of transmission to dogs was detected. [less ▲]

in 31th Congress of the International Union of Game Biologists, Abstract Book (2013, August 27)

Schmallenberg virus (SBV) is a recently discovered vector-borne Orthobunyavirus targeting ruminants. It is transmitted by Culicoides biting midges and caused a large outbreak in European sheep and cattle ... [more ▼]

Schmallenberg virus (SBV) is a recently discovered vector-borne Orthobunyavirus targeting ruminants. It is transmitted by Culicoides biting midges and caused a large outbreak in European sheep and cattle populations in 2011 and 2012. The infection of adults was associated with a drop in milk production, fever and diarrhea. But the virus was further shown to cross the placental barrier and to be responsible for a hydrocephaly/arthrogryposis syndrome in calves and lambs. After its occurrence in 2011 in Germany, SBV quickly spread across Europe and in spring 2012 more than 90% of Belgian domestic cattle had seroconverted. To assess the susceptibility of wild ruminants to the infection, a total number of 547 and 494 sera, from red (Cervus elaphus) and roe deer (Capreolus capreolus), respectively, were collected during the hunting seasons 2010 to 2012 and tested for the presence of anti-SBV antibodies. While no samples from 2010 revealed to be positive, about two-thirds of red deer and half of roe deer sampled in 2011 were seropositive. In 2012, the seroprevalence dropped to 33% in red deer and remained stable in roe deer. The high seroprevalence rates found in both species in Belgium shows that wild ruminants are susceptible to the infection by SBV. If the infection of deer was associated to a hydrocephaly/arthrogryposis syndrome similar to that observed in domestic ruminants is still unknown. There is currently no evidence of such a transplacental passage in red or roe deer. The decrease in the seroprevalence observed in red deer in 2012 might be the result of the turn-over in the red deer population and reflect an absence of virus circulation in 2012. Further investigations in the upcoming years will help to enlighten this point. [less ▲]

in Lecoq, Yves (Ed.) 31th Congress of the International Union of Game Biologists (2013, August 27)

In the summer/fall of 2011, a nonspecific febrile syndrome characterized by hyperthermia and drop in milk production with occasional reports of watery diarrhea and abortion was reported among dairy cows ... [more ▼]

In the summer/fall of 2011, a nonspecific febrile syndrome characterized by hyperthermia and drop in milk production with occasional reports of watery diarrhea and abortion was reported among dairy cows on farms in northwestern Europe. Further, in November 2011, an enzootic outbreak of malformed neonates emerged in several European countries, with stillbirth and birth at term of lambs, kids and calves with neurological signs or malformations of the head, spine, or limbs. Both syndromes were associated with the presence in the blood (adults) or in the central nervous system (newborns) of a new Shamonda/Sathuperi-like orthobunyavirus, provisionally named Schmallenberg virus (SBV) after the town in Germany where the first positive clinical samples were identified. Defining as precisely as possible the host range of the newcomer is a key point to predict the outcome of the emergence of SBV disease in Europe. In this respect, it must be pointed out that orthobunyaviruses infect more animal species than those in which the foetus is damaged. Recently, serological evidence for SBV infection in wild ruminant species (Cervus elaphus and Capreolus capreolus) was reported (Linden et al., 2012). In the present study, the objective was to seek after serological evidence of SBV infection among wild boars living in a geographical area where exposure to infected insect vectors was high in 2011, as judged from the very high seroprevalence reported among cattle in that region. About 700 animals were sampled during the 2010-2012 hunting seasons. All serum samples collected during the fall of 2010 were seronegative. On the contrary, apparent seroprevalence among wild boars in 2011 was ~27% and started to decline in 2012 (~11%). Acquired immunity against the new virus was thus already very high in the wild boar populations sampled in the fall 2011, suggesting that the new virus had quickly spread throughout the region since its emergence about 250 km northeast in the late summer 2011. The drop in seroprevalence recorded in 2012 suggests that the virus was no more circulating in the region. [less ▲]